Найти сумму всех четных элементов массива

uses crt;
var
a:array[1..100]of integer;
i,n,s:integer;
begin
s:=0;
writeln('skoka chisel?');
readln(n);
if n>100 then n:=100;
randomize;
for i:=1 to n do begin
a[i]:=random(100);
write(a[i]:3);
if (a[i] mod 2=0) and (i mod 2=0) then s:=s+a[i];
end;
writeln;
writeln(s);
readln;
end.

uses crt;
var
a:array[1..100,1..100]of integer;
i,j,n,m,s:integer;
begin
s:=0;
writeln('skoka chisel?');
readln(n,m);
if n>100 then n:=100;
if m>100 then m:=100;
randomize;
for i:=1 to n do begin
for j:=1 to m do begin
a[i,j]:=random(100);
write(a[i,j]:3);
if (a[i,j] mod 2=0) then s:=s+1;
end;
writeln;
end;
writeln(s);
readln;
end.

uses crt;
const n=3;
      m=4;
var a:array[1..n,1..m] of real;
    b:array[1..n] of real;
    i,j:integer;
    s:real;
begin
ClrScr;
Randomize;
for i:=1 to n do
 begin
  for j:=1 to m do
   begin
    a[i,j]:=-10+random(20);
    Write(a[i,j]:5:1);
   end;
  Writeln;
 end;
Writeln;
for i:=1 to n do
 begin
  b[i]:=a[1,1];
   for j:=1 to n do
    if a[i,j]>b[i] then
     b[i]:=a[i,j];
 end;
Writeln;
s:=0;
for i:=1 to n do
 s:=s+b[i];
Writeln('Sum ',s:0:1);
Readln;
end.

b[i]:=a[i,1];

b[i]:=a[i,1];
   for j:=1 to m do